chore(test): extract test data generation for RBAC tests (#1878)

## Description

This PR works on improving our test data generation strategy for RBAC
tests. It moves static test data to a separate file without making other
changes to support a follow-on PR.

End to End Test:  <!-- if applicable -->  
(See [Pepr Excellent
Examples](https://github.com/defenseunicorns/pepr-excellent-examples))

## Related Issue

Relates to #1329 

## Type of change

- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [x] Other (security config, docs update, etc)

## Checklist before merging
- [x] Unit,
[Journey](https://github.com/defenseunicorns/pepr/tree/main/journey),
[E2E Tests](https://github.com/defenseunicorns/pepr-excellent-examples),
[docs](https://github.com/defenseunicorns/pepr/tree/main/docs),
[adr](https://github.com/defenseunicorns/pepr/tree/main/adr) added or
updated as needed
- [x] [Contributor Guide
Steps](https://docs.pepr.dev/main/contribute/#submitting-a-pull-request)
followed

Co-authored-by: Case Wylie <[email protected]>